<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        class Person {
            static instance = null ; 
            constructor(name){
                if (!Person.instance){
                    Person.instance = this ; 
                } else {
                    return Person.instance ; 
                }
                this.name = name ; 
            }
        }
        let zhangsan = new Person("张三");
        let zhangsan1 = new Person("张三1");
        let zhangsan2 = new Person("张三2");
        console.log(zhangsan,zhangsan1,zhangsan2);
    </script>
</body>
</html>